Brain indices of nonconscious associative learning.
Using a classical conditioning technique, this study investigated whether nonconscious associative learning could be indexed by event-related brain activity (ERP). There were three phases. In a preconditioning baseline phase, pleasant and unpleasant facial schematics were presented in awareness (suprathreshold). A conditioning phase followed, in which stimuli were presented outside awareness (subthreshold, via energy masking), with an unpleasant face (CS+) linked to an aversive shock and a pleasant face (CS-) not linked to a shock. The third, postconditioning phase, involved stimulus presentations in awareness (suprathreshold). Evidence for acquisition of a conditional response was sought by comparing suprathreshold pre- and postconditioning phases, as well as in the subthreshold conditioning phase itself. For the pre-postconditioning phase analyses, significant ERP component differences differentiating CS+ and CS- were observed for N1, P2, and especially P3. For the conditioning phase, significant differences were observed in the 100-400 ms. post-stimulus region reflecting a CS+ processing negativity. Brain activity does indeed index the acquisition of a conditional response to subthreshold stimuli. Associative learning can occur outside awareness.
Wong
P S
PS
Department of Psychology, New School for Social Research, New York, New York 10003, USA. pswong@newschool.edu
Bernat
E
E
Bunce
S
S
Shevrin
H
H
D000328:Adult; D001245:Association Learning / Q000502:physiology*; D001921:Brain / Q000502:physiology*; D003213:Conditioning, Psychological; D003243:Consciousness / Q000502:physiology*; D005071:Evoked Potentials; D006801:Humans; D008297:Male; D010470:Perceptual Masking